Deep-Sea Diving: Jacques Piccard and Donald Walsh Pilot the Trieste to a Record Depth of 35,800 Feet in the Mariana Trench in the Pacific Ocean

Overview

The greatest ocean depth yet located is the Challenger Deep, a part of the Mariana Trench that descends to a depth of 36,201 feet—almost seven miles down. While this great depth has not yet been reached, on January 23, 1960, the Trieste descended to 35,800 feet (10,912 meters), the greatest depth yet reached by man. This descent showed that the technology had been developed to take people virtually anywhere on Earth and that, just seven years after Mount Everest had been scaled, the depths of the sea had been conquered too. The technology that went into designing and building Trieste was later used for other research vessels and military submarines. It spurred developments that led to the remotely operated vehicles that discovered the Titanic and recovered the treasure of the Central America in the 1990s.

Background

Slightly over 70 percent of the Earth's surface is covered by ocean. Until the last decade of the twentieth century, however, more was known about the surfaces of Venus and Mars than was known about what lay beneath the oceans. In fact, for most of history men sailed on the surface of the ocean and submarines navigated the topmost few hundred meters, but the only ships that visited the ocean floor were those that sank, never to return.

Part of the reason for this lack of direct knowledge is sea pressure. The weight of a column of seawater increases by 44 pounds per square inch (psi) (3.1 kg/m²) for every 100 feet(30.5 m) of depth. A mere 100 feet of seawater, then, will exert a pressure of 44 psi over each of the 144 square inches (929 cm²) in one square foot (0.9 m²⁾for a pressure of 6,336 pounds (2,877 kg). In other words, a vessel with only one square foot of hull would have three tons(2.72 tonnes) of force acting against it at a depth of only 100 feet. The Challenger Deep, at a depth of about 36,000 feet (10,973 m) experiences a pressure of almost eight tons per square inch (11,249,112 kg/m²⁾. Pressure alone is sufficient to keep people from venturing to these depths without taking extraordinary measures. Add to this equation the necessity to breathe, maneuver, and return to the surface and one begins to understand why the ocean depths were not visited until 1960 and why, even today, they are known chiefly only by indirect means.

In the 1950s a number of advances came together that began to make human visitation of the sea floor possible. Science gave us high-strength metals capable of withstanding the intense pressures that exist at great depths, while other advances helped make life-support systems that could keep people alive underwater for the many hours required to make a round trip to great depths. The engineering that went into designing better submarines in the post-World War II era also helped make deep-diving submersibles that could be steered, while advances in electrical engineering went into designing the lighting systems that allowed occupants to see during their dives. Finally, global politics spurred the International Geophysical Year (1957-1958), giving further impetus to explore the sea while the emerging possibilities of submarine warfare, seafloor ballistic missiles, and other military uses of the ocean gave navies a vested interest in learning more about the ocean and its floor. All of these trends intersected in the 1950s, leading to the design of the Trieste, the first submersible designed to travel to and return from the deepest parts of the ocean.

In 1953 Swiss oceanographer Jacques Piccard (1922- ) helped his father Auguste Piccard (1884-1963) build the Trieste, which they dove to a depth of 10,168 feet off the Mediterranean island of Ponza. In 1956, under contract with the U.S. Navy, the Piccards redesigned the Trieste to withstand the pressure of any known sea depth; they sold the Trieste to the navy two years later. In 1960, accompanied by U.S. Navy Lieutenant Don Walsh, Jacques Piccard took the Trieste to the bottom of one of the deepest parts of the Mariana Trench, the Challenger Deep, where they touched bottom at a depth of 35,800 feet (10,912m), just 400 feet (122m) less than the deepest sounding recorded.

Impact

The Trieste's visit to the bottom of the Mariana Trench resulted in a number of effects on science, engineering, and society. Some of the more important of these are:

Opening the ocean depths to direct exploration
Development of deep-sea technology used in a number of areas
Exciting the public interest in oceanographic exploration and marine biology at great depths

Each of these areas will be explored in greater detail in the remainder of this essay.

Before the Trieste's descent, man's direct exploration of the oceans was limited to the uppermost few thousand feet, whereas the average depth of the oceans is over 20,000 feet (6,096 m). The continental shelves and areas near some islands could be observed directly, but very little else. All other deep-sea exploration was done by casting nets or dredges over the side of a vessel, dragging them along the ocean floor, and hauling them back to the surface. Because of such crude methods, the deep sea floor was thought to be lifeless.

This perception began to change in the 1950s when Jacques Cousteau (1910-1997) and Harold Edgerton (a professor at the Massachusetts Institute of Technology) developed the technology to take pictures at great depths. These photos showed evidence of life at virtually all depths and locations, gradually convincing marine biologists that life could exist even under the crushing pressures of the abyssal plains. Trieste's visit showed life existed even at the deepest point on the planet; exploration by other vessels has confirmed that living communities inhabit most parts of the ocean bottom. This discovery, particularly the recent discovery of thriving communities around deep-sea hydrothermal vents, has caused biologists to reconsider questions of where life might have evolved and whether or not life may exist elsewhere in the solar system. The first few decades of the twenty-first century may see a submersible probe explore oceans thought to underlie the icy surface of Jupiter's moon, Europa, in search of extraterrestrial deep-sea life.

Trieste also helped to consolidate many advances in submersible design and to inspire other designers. As noted above, many advances came together to create Trieste. Her success encouraged others to design and build other vessels to explore the ocean. Jacques Piccard went on to invent the mesoscaph (in which "meso" means "middle"), a vessel for exploring intermediate ocean depths; the United States built the FLIP (floating instrument platform) to study near-surface oceanography and marine biology. In addition to these vessels, Alvin, Deepstar, and the navy's deep submergence rescue vehicle (designed to rescue crews from sunken submarines) were designed using lessons from Trieste. Some features of modern deep-diving nuclear submarines are the result of work that went into Trieste's design as well.

In addition to the engineering and scientific advances represented by the Trieste, she and other deep-sea exploratory vessels excited the public's interest in oceanography, an interest that has carried on for several decades. The interest shown for most of the last half of the twentieth century was probably due mainly to the efforts of Jacques Cousteau, but the bizarre nature of deep-sea life has been sufficiently interesting to capture public attention in and of itself. In fact, deep-sea exploration often provokes newspaper headlines, stories in the nightly news, or feature articles in popular magazines. In addition to scientific discoveries, events such as the recovery of gold from the sunken ship Central America, the live broadcast from the wreck of the Titanic, and other events routinely command large television audiences. As with so many other oceanographic exploits, the technology that makes such deep submergence possible is a direct outgrowth of lessons learned while designing, building, and operating Trieste, including her dive into the Challenger Deep.

Finally, in a related vein, deep-sea exploration became important to the United States in the late 1950s and early 1960s as compensation of a sort for the Soviet Union's successes in space. The U.S.S.R. launched the first satellite and the first manned spaceflight as well as conducted the first spacewalk, all of which dealt temporary blows to the idea of the United States as a leading technological power and innovator. Moreover, while trying to catch the Soviet Union in space, the United States suffered a number of embarrassing rocket failures. At times, the only consolation for the United States seemed to be the American mastery of deep-sea technology and exploration.

In spite of the Trieste's success and that of other manned and unmanned deep-sea exploration vessels, the bottom of the sea remains largely a mystery to science. The release of data from military satellites has been a tremendous boon to mapping the seafloor but provides no information about the organisms that exist there and how they live. Research on these communities of organisms is providing important information that will likely lead to a better understanding of the origins of life on earth and how that early life existed. These questions are of widespread scientific and popular interest, especially given the strides taken in the late 1990s in the search for life on other planets. In addition, rich deposits of metal nodules—mostly manganese and related metals—exist on the ocean's abyssal plains but, in spite of their economic potential, currently remain untouched. For these reasons, the Trieste's 1960 dive to a depth of nearly seven miles ranks as a high accomplishment as well as sets the stage for even more dramatic achievements to come.

P. ANDREW KARAM

Further Reading

Piccard, Jacques. "Man's Deepest Dive." National Geographic (May 1960).